Manufacturing process for laminated cards with intermediate PETG layer

ABSTRACT

The invention involves a card, including a card body including at least three laminated plastic layers directly superimposed on each other, a second layer being a layer in polyethylene terephthalate glycol placed between a first layer and a third layer, the first layer and third layer being of a chemical nature different from that of said second layer, and an electronic module being incorporated in a cavity of the card body, the module including an integrated circuit, where the thickness of the second layer is of the same order of magnitude as that of the first and third layers, and wherein the cavity extends into the second layer from the first layer.

FIELD OF THE INVENTION

The invention concerns a manufacturing process for laminated cards, andcards obtained by means of a process of this type.

The cards according to the invention are chip cards comprising a plasticcard body, and an electronic module integrated in said card body,comprising an integrated circuit the contact pads of which are connectedto other pads flush with the surface of the card body and/or theterminals of an antenna embodied in said card body.

Cards of this type are principally designed for processing or storingconfidential data, for example for the purpose of executing electronictransactions in a variety of domains such as health care, pay TV,telephony and banking.

Cards of this type are generally personalized in -such a way as toidentify their holders, and consequently carry printed marks for thispurpose.

BACKGROUND OF INVENTION

Various processes are known for the manufacture of cards. Some processesinvolve hot lamination. According to these processes, the differentlayers forming the body of the card are assembled at given pressures andtemperatures, such that the plastic materials used in their manufacturereach their setting point, and inter-penetrate locally to create largelycoherent laminated assemblies. These assemblies are then printed and cutto the required dimensions for a card body. A cavity is then milled ineach body, and an electronic module is finally inserted and bonded insaid cavity.

In these processes, the known materials used in the construction of thevarious layers are acrylonitrile butadiene styrene (ABS), polyvinylchloride (PVC), ABS/PVC mixtures, polyethylene terephthalate (PET),polyethylene terephthalate glycol (PETG) and polycarbonate (PC).Frequently the various layers constituting the card body are of the samechemical nature, for example, all in PVC. In particular, the varioussuperimposed layers in known PETG cards are all in PETG.

The manufacturing processes for state of the art cards, and cardsobtained using processes of this type, nevertheless present a number ofdrawbacks.

In particular, cards in ABS, PVC, ABS/PVC mixtures, PET and PC showlimited resistance to dynamic, longitudinal and lateral bending. Ingeneral, they crack after about 1,500 dynamic longitudinal bends, with a20 mm deflection centered on the card body, and about 1,500 lateraldynamic bends with a 10 mm centered deflection.

However, this is not the case with cards in PETG, which on the contrary,show good resistance to the above bending loads. Nevertheless, given thelow viscosity of PETG at normal laminating temperature and pressureconditions, it is necessary to reduce laminating temperatures at a givenpressure, to avoid all the drawbacks of PETG creep in the laminatingequipment. However, at these reduced temperatures, the coherence of thelaminated assemblies obtained is found to be mediocre, and it isdifficult in practice to find a compromise which makes it possible toavoid both PETG creep problems and the coherence drawbacks of saidlaminated assemblies at the same time.

SUMMARY OF THE INVENTION

The invention concerns a contact-free chip card, comprising a card bodyincorporating an antenna coupled to an electronic circuit. The card bodycomprises two outer layers and one intermediate layer placed between thetwo outer layers. The intermediate layer incorporates the antenna andelectronic circuit. Each outer layer is connected to the intermediatelayer via a bonding layer, for which the melting point is below that ofsaid outer layers.

In view of the foregoing, a problem which the invention proposes tosolve is the manufacture of a card with, on the one hand, a card bodyincorporating at least three laminated plastic layers directlysuperimposed on each other, with the second layer placed between thefirst and third layers, and an electronic module incorporated in saidcard body, said module comprising an integrated circuit, said cardshowing good resistance to dynamic bending, and for the manufacture ofwhich the problems of creep and coherence are satisfactorily overcome.

Considering the above-mentioned problem, the first objective of thesolution proposed by the invention is a manufacturing process for a cardof this type, characterized by the fact that the second layer being alayer in polyethylene terephthalate glycol, and the first and thirdlayers being of a different nature to said second layer,—the first,second and third layers are laminated so as to obtain a first laminatedassembly,—a cavity is executed in the second layer,—and the module isinserted in said cavity.

In this way, the PETG is contained between the first and third layers,and does not creep during lamination.

The resultant card also has good coherence, the plastic materials of thethree layers having reached their setting point, and the resistance ofsaid card to dynamic bending is better than that for state of the artcards.

The process according to the invention has the advantage of including asubsequent step whereby—said first laminated assembly, in which themodule has been inserted, is laminated under temperature and pressureconditions such that the PETG reaches its setting point so that a secondlaminated assembly is obtained.

The PETG, which has low viscosity under the conditions defined above,then fills the space between the edges of the cavity and the edges ofsaid module, thus ensuring that the module is held firmly in place inthe card body.

Another advantage resulting from this step appears when the secondlamination, using an operating method particular to the invention, isexecuted in the presence of a fourth plastic layer. This plastic layerdoes not undergo the strains normally encountered.

It should be noted that the second objective of the invention is toobtain a card characterized by the fact that said second layer is alayer of polyethylene terephthalate glycol, and that the first and thirdlayers are of a chemical nature different from that of said secondlayer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingnon-exhaustive description, based on the attached drawings where:

FIG. 1 shows a perspective view of a card according to the invention;

FIG. 2 shows a cross-section view of a card according to the invention;

FIG. 3 illustrates, in a cross-section view, a step in the laminationprocess according to the invention;

FIG. 4 illustrates, in a cross-section view, a module insertion stepaccording to the invention; and

FIG. 5 illustrates, in a cross-section view, a step in the laminationprocess according to the invention.

DETAILED DESCRIPTION

As shown in FIG. 1, card 1 according to the invention comprises cardbody 2 and electronic module 3 incorporated in said card body 2.

Card body 2 is in the form of a rectangular parallelepiped, thedimensions of which, in accordance with standard ISO 7816, the contentof which is incorporated in this description by reference are of theorder of 85.6 mm (length), 54 mm (width), and 0.8 mm (thickness).

The card body comprises different laminated plastic layers, directlysuperimposed on each other. The term “directly superimposed” means thatthe plastic layers are in direct contract with each other, or in contactwith each other via a bonding agent.

Marks 4, such as a bar code, biometric data or a photograph of theholder of card 1, are generally printed on the card. Marks 4 can appearon either or both the main faces of card body 2.

For the manufacturing method illustrated in FIG. 2, card body 2comprises four directly superimposed plastic layers. These comprisefirst plastic layer 5, second layer 6, third layer 7, and fourth layer8. First layer 5 is a thermoplastic PVC layer, for which the settingpoint is of the order of 73° C., and the thickness is about 190 μm.Second layer 6 is a thermoplastic PETG layer, for which the settingpoint is of the order of 70° C., and the thickness is about 190 μm.Third layer 7 is a thermoplastic PVC layer, for which the setting pointis of the order of 73° C., and the thickness is about 240 μm. Fourthlayer 8 is a plastic layer the thickness of which is the order of 175μm, which can be in PVC or any other clear plastic material. First layer5 is directly superimposed on second layer 6 which is directlysuperimposed on third layer 7, which is directly superimposed on fourthlayer 8. Second layer 6 in PETG is thus placed between first layer 5 andthird layer 7 both of which are in PVC. First layer 5 and third layer 7are of a chemical nature different from that of the PETG of the secondlayer.

Electronic module 3 is incorporated in card body 2, in a positiondefined, for example, in the above.-mentioned ISO standard. Module 3 hastwo main parts: module body 9 embedded in card body 2, and not visiblefrom the exterior, and upper “contact” part 10, comprising contact pads11 flush with the surface of card body 2. Module body 9 incorporatesintegrated circuit (chip) 12, contact pads 13 of which are connectedelectrically, by metal wires 14, to contact pads 11, the assemblycomprising integrated circuit 12 and wires 14 being coated withprotective resin 16 and reinforced, where appropriate, by a sheet ofepoxy, while upper part 10 comprises, in addition to contact pads 11,epoxy support 17 drilled with holes to take wires 14 for connection ofintegrated circuit 12 to said contact pads 11.

In accordance with a particularly advantageous aspect of the invention,the PETG of second layer 6 is in direct contact with module body 9.

The procedure for manufacture of a card in accordance with the inventionis as illustrated in FIGS. 3 to 5.

As illustrated in FIG. 3, first layer 5, second layer 6, and third layer7 are superimposed between plates 18 of a laminating press. Thesuperimposed assembly is then subjected to a first laminating operation,under the pressure and temperature conditions as defined in thefollowing example, where the assembly is raised to a temperature of 115°C., subjected to a pressure of 50 bar for 1 minute, and then to apressure increasing linearly from 50 bar to 150 bar for 15 minutes. Thispressure of 150 bar is then maintained for 4 minutes. The superimposedassembly is then subjected to a pressure exceeding 250 bar for 17minutes at ambient temperature. This produces a first laminated assemblyin which first layer 5, second layer 6, and third layer 7 are bondedtogether, the plastic materials of said layers having reached theirsetting point during the first lamination.

The PETG, the viscosity of which is particularly low once the settingpoint has been reached, is contained between first layer 5 and thirdlayer 7. The PETG does not spread between plates 18.

Naturally, the steps of the process according to the invention describedabove are executed preferably on sheets of large dimensions, for exampleof the order of 610 mm long by 475 mm wide. The laminated assembliesthen obtained with these large-dimension sheets are cut to obtain aboutfifty laminated assemblies of card format size.

In a subsequent step in accordance with the invention as illustrated inFIG. 4, cavity 19 is executed, for example by milling, in the firstlaminated assembly. Cavity 19, designed to receive module 3, ispresented in the form of a symmetrical, blind hole of revolution, flaredat its top where it presents a shoulder. Cavity 19 penetrates firstlayer 5 and emerges on second layer 6. As shown in FIG. 4, cavity 19emerges in second layer 6 and reaches third layer 7.

Module 3 is then inserted in said cavity 19. In practice, module 3 isbonded in cavity 19, the adhesive being located on the shoulder designedto receive upper part 10 of said module 3. A laminated assembly isfinally obtained in which module 3 has been incorporated.

This laminated assembly, incorporating module 3, can be stocked, ordistributed by card manufacturers to administrative authorities orcompanies wishing to distribute small quantities of cards. Theseadministrative authorities or companies can be equipped with “office”type laminating and personalization tools, operating card by card at lowoutput rates.

FIG. 5 illustrates a complementary step in accordance with theinvention, which can be undertaken by administrative authorities andcompanies.

The first laminated assembly, incorporating module 3, is directlysuperimposed on the fourth layer in a card by card laminating tool. Thesuperimposed assembly thus obtained, or second superimposed assembly, isthen laminated following a cycle during which said assembly is raised,for example, to a temperature of 150° C. for 4 to 5 seconds, and thencooled progressively to 45° C., at which temperature it is maintainedfor about 5 minutes at a pressure of the order of 4 to 5 bar.

During this second laminating operation, the PETG reaches its settingpoint, liquefies and fills the space between the edges of the modulebody and the edges of the cavity. Fourth layer 8 is not then subject tolocal strain plumb with module 3, due, in the state of the art, to thefact that it is crushed in the above-mentioned space. Card 1 accordingto the invention shows no topological or visual fault plumb with saidmodule. It is thus possible to personalize the card body physically, forexample by printing marks 4 on layer 8. In certain execution variantsfor said layer 8, printing inks are sublimated and migrate via saidlayer 8, increasing the security of card 1.

Cards 1 in accordance with the invention only crack after about 4,500longitudinal dynamic bends, and 4,500 lateral dynamic bends, withrespective deflections of 20 and 10 mm.

Naturally, the execution methods described above are in no waylimitative, and the invention can be applied to the manufacture ofcontact-free cards, in which the module, generally comprising theintegrated circuit, is connected to the terminals of an antenna embeddedin the card body, without any problem.

What is claimed is:
 1. A card comprising a card body including at leastthree laminated plastic layers directly superimposed on each other, asecond layer being a layer of polyethylene terephthalate glycol placedbetween a first layer and a third layer, said first layer and thirdlayer being of a chemical nature different from that of said secondlayer, an electronic module being incorporated in a cavity of said cardbody, said module comprising an integrated circuit, wherein thethickness of said second layer is of the same order of magnitude as thatof said first and third layers, and wherein the cavity extends into thesecond layer from the first layer, and wherein the electronic module issecured within the cavity by liquefied polyethylene terephthalate glycolfrom the second layer.
 2. A manufacturing process for a card comprisinga card body including at least three laminated plastic layers directlysuperimposed on each other, a second layer being a layer of polyethyleneterephthalate glycol placed between a first layer and a third layer,said first layer and third layer being of a nature different from thatof said second layer, an electronic module being incorporated in saidcard body, said module comprising an integrated circuit, comprises thesteps of: laminating said first layer, second layer, and third layertogether so as to obtain a first laminated assembly, said second layerhaving a thickness of the same order of magnitude as that of said firstand third layers; creating a cavity extending into the second layer fromthe first layer; inserting said module in said cavity; and liquefying atleast a portion of the second layer such that liquefied polyethyleneterephthalate glycol flows into said cavity to secure said module.
 3. Amanufacturing process for a card comprising a card body including atleast three laminated plastic layers directly superimposed on eachother, a second layer being a layer of polyethylene terephthalate glycolplaced between a first layer and a third layer, said first layer andthird layer being of a nature different from that of said second layer,an electronic module being incorporated in said card body, said modulecomprising an integrated circuit, comprises the steps of: laminatingsaid first layer, second layer, and third layer together so as to obtaina first laminated assembly, said second layer having a thickness of thesame order of magnitude as that of said first and third layers; creatinga cavity extending into the second layer from the first layer; andinserting said module in said cavity, wherein during a second laminationstep the system comprising said first laminated assembly and said moduleis laminated so as to obtain a second laminated assembly, said secondlamination step being executed under pressure and temperature conditionssuch that the polyethylene terephthalate glycol reaches its Vicat pointand flows into the cavity.
 4. The process according to claim 3, whereinsaid first laminated assembly is laminated directly superimposed on afourth layer.